Rosacea is, while rare among colored races, common among races with a light-colored skin, especially white races, and many cases occur among them. It is divided according to the symptoms into the first degree (telangiectatic rosacea on the forehead, cheeks, dorsum nasi), the second degree (acne rosacea, coexistence of follicular papules and pustules), and the third degree (rhinophyma, dark red tumor and dilated pore on apex nasi). It starts with facial flush (redness) and eventually involves serious impairment of appearance, developing papules, pustules, rhinophyma and tumor on apex nasi, It is also accompanied by seborrhea or enhancement of feeling of heat on the face due to emotional stress or change of environmental temperature. Thus, these symptoms give a patient mental and physical suffering.
For the time being, the real cause of rosacea is unknown (Hifuka Chirya Handbook, pp. 380-381, Nanzando (1987) and Gerd Plewing, Albert M. Kligman, ACNE and ROSACEA, 2nd, Completely Revised and Enlarged Edition, pp. 431-454, Springer-Verlag (1993)). Rosacea is apt to be confused with acne, what is called pimple, classificationally. Rosacea, which can coexist with acne, essentially differs from acne. It is characterized by facial flush due to vascularization and proceeds with acne rosacea and tumor on apex nasi. A digestive disease, hypertension, Demodex folliculorum, emotional stress, hereditary predisposition, etc. have been pointed out as a conceivable cause of rosacea, which has not been ascertained yet.
Therefore, there is no drug established as a remedy for rosacea, and the only method available now is symptomatic treatment, such as administration of minocycline or tetracycline antibiotics for the treatment of delayed skin diseases, use of metronidazole (anthelmintic), removal of mental stress, dietetic treatment, and supplemental concomitant use of vitamin B.sub.2 or B.sub.6.
Accordingly, it has been keenly demanded to study and develop more useful treating agents for rosacea.
An object of the present invention is to provide a useful rosacea treating agent.